This invention relates generally to cathode ray tubes (CRTs) and is particularly directed to an arrangement for stabilizing the operation of a CRT over a wide temperature range.
The miniaturization and ruggedization of CRTs have substantially increased the applications for which they are used in displaying visual information. For example, the use of CRTs in automobiles to visually present operating and status information to the vehicle operator represents one of the more recent, large scale uses for CRTs.
Some of the new environments in which CRTs can be found impose substantially more demanding operating criteria upon the CRT. For example, a CRT in an automobile may be subjected to an operating temperature range in excess of 120.degree. F. Because of the negative temperature response of conventional high voltage circuitry which supplies the CRT, prior art approaches have exhibited reduced brightness of the video display at high operating temperatures and excessive brightness at low operating temperatures.
The present invention eliminates the aforementioned problem encountered in the prior art by providing a temperature compensated DC supply circuit for energizing the G2 grid of a CRT in ensuring substantially constant brightness in the CRT's video display over a wide temperature range.